My suggestion for new people reading in 2021 is to 1) don’t rely on forums for solid information as most folks may not know any more than you do.. read for enjoyment, support, and some tips but if you want true tested hydroponics information go to the experts who raise food, or more and more, weed — day in and day out 24/7, 365 days a year, decades on. Go to university sites who have done the testing and studies, check hydroponics magazines and commercial growing hydroponic website. Look for a commercial site near you that has done it for 10+ years,mand see if they will mentor you, or maybe you can get a part time job. A great magazine is Maximum Yield. It is subscription based, but you can read many of the articles for free. Due to cannabis laws, there is a bit of hop/skip on entry just like liquor sites. This is of course, as many already know, a cannabis magazine but it has morphed into so much more and is beneficial to anyone trying to understand the chemistry of all horticulture along with lightening, heating, cooling, ventilation, propagation, other climate control, growing media, how plants grow (hormones, photosynthesis, etc) and other subjects towards indoor growing. In fact many items are good in general no matter the growing type. It’s used by most commercial cannabis establishments, and more and more other type of plants too. There may be some other reputable magazines out there oriented to cannabis but I’m not sure. There are also magazines for greenhouse growing (anything from orchids, bedding plants, to tomatoes, cukes, etc) - like Greenhouse Grower. This and other industry magazines you can get free, you have to fill out a form each year saying yes you want it and then they will mail it to you. Or you can go on-site and read it. The issue of annual “yes I want it” is so they get lower mailing rates, and more importantly, to prove to advertisers the number of people who read it. It’s very important to trade magazine production. You can search for free trade publications on any industry in the world - just search “trade magazine and the name of the industry”.
Here is a website to find some other horticultural/greenhouse, etc. they all have information that many can use even if not specific to cannabis:
https://www.waltersgardens.com/article.php?ID=166
That said... don’t use house insulation form of rock-wool to grow plants. People doing that give it bad name just as people who use the horti product think it doesn’t work for home insulation — “it stays too wet”. You get the idea. You need the right product for the right location and though the base is the same...it’s the treatment or lack of treatments in each that’s the difference. A great example is perlite —Most people think if it as the white stuff in potting soil. Some know it’s a natural expanded product but that’s it. Perlite comes in different forms, sizes, and is used in everything from fire protection, to building construction, to mix with concrete, to insulation for homes, pools, etc and to horticultural uses. Check out the Perlite Institute....yes there is such a thing! You may be surprised. It’s a great product that doesn’t get its due.
Good luck.